Mix the cream and milk together and pour 200ml (3/4 cup + 4 teaspoons) into a small saucepan and very gently heat on a low heat.
Chop the dark chocolate into pieces and add to the saucepan. Heat gently, stirring occasionally, until hot and thoroughly melted.
Meanwhile, pour 200ml (3/4 cup + 4 teaspoons) cold water into a bowl and stir in the Vege-Gel. Transfer to a small saucepan and heat through, stirring, until just about boiling. Then reduce the heat to very low to keep the Vege-Gel in liquid form.
Quickly stir one third of the liquid Vege-Gel into the dark hot chocolate milk and mix well. Divide the mixture between 6 x 200ml (7 fl.oz) heatproof glass dishes. Leave aside to cool (the mixture will set quickly as it cools).
Pour another 200ml (3/4 cup + 4 teaspoons) cream and milk mixture into a small saucepan. Break up the Milk Chocolate into pieces and add to the saucepan. Heat gently, stirring occasionally, until hot and thoroughly melted.
Stir in half of the remaining liquid Vege-Gel until well mixed. Divide between the 6 glasses, pouring gently over the dark chocolate layer and cool as before.
Repeat the heating and melting process using the remaining cream and milk mixture with the White Chocolate. Add the Madagascan Vanilla Extract and the remaining liquid Vege-Gel. Mix it all in together quickly.
Pour the white chocolate mix into the 6 glasses over the milk chocolate layer and leave to fully cool down.
Chill the desserts for at least 2 hours before serving. Sprinkle with grated Dark Chocolate to decorate and extra chocolate sprinkles if you want to.